These pickled onions should provide a bit of warmth when they are ready in the new year, the spicy pickling vinegar is added to by tucking a few chillies in the jars.
I used up the remainder of a 5 kg bag of onions I recently bought for the bargain price of £3.75, much more cost effective than buying small bags from the supermarket.
The first half of the bag had gone in making sweet pickled onions.

This hot and spicy recipe used spicy pickling vinegar.

Recipe Costs

£1.87 2.5kg pickling onions
£0.19 500g salt
£0.75 1 litre malt vinegar
£0.10 1 tsp coriander seeds
£0.03 1 tsp mustard seeds
£0.20 4 tsp cumin seeds
£0.26 5 cardamons £0.19 5 cloves
£0.10 10 g fresh ginger
£0.03 1 tsp garam marsala (whole, not ground)
£0.24 4 fresh chillis
£3.86 Total
£1.54 per kg of onions (about quarter the cost of traditional pickled onions (not budget ones) from tesco)

This mix of spices would be great even without the extra chillies, I choose a good selection of seeds making sure there were about 15g - 30g to each litre of vinegar. These were then added to the vinegar and brought to the boil, then left to stand overnight. You could use a Spice Bag , but I just make sure I strain the vinegar carefully.

The onions are topped, tailed and peeled, then mixed with the salt and left to stand overnight as well.

The next day they are rinsed, and almost look good enough to eat already. The salt has removed a large amount of water which should make them nice and crunchy.

The onions are packed into sterilised jars, I find if you push them down you can get them to fit nice and tight and the top layer tucks pleasingly under the shoulder of the jar.
I decided to put two half chillies in each jar, time will tell if this is being overly keen.

The end result looks good and will be left to mature for several months in a cool dark cupboard.

Recipe Timings

30 mins peeling and salting
10 mins preparing vinegar
overnight salting and cooling
15 mins potting

Taste Test

Very spicy, not for the faint hearted.
I would probally halve the amount of chillis in the jar next time as I could only manage to eat these onions chopped up in a sandwich.